MOLECULAR BASIS OF IMMUNOGLOBULIN GENE HYPERMUTATION

免疫球蛋白基因超突变的分子基础

• 批准号: 3459484
• 负责人: William L. Carroll
• 金额: $ 9.03万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-12-01 至 1994-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3459484
• 关键词: B lymphocyte; Escherichia coli; antibody formation; blood /lymphatic neoplasm; cell differentiation; cell transformation; gene mutation; gene rearrangement; genetic markers; genetically modified animals; immunoglobulin genes; laboratory mouse; microorganism genetics; molecular cloning; molecular genetics; plasmids; protein sequence; tissue /cell culture; transfection; transposon /insertion element

Further diversification of the preimmune antibody repertoire is provided by a unique process of immunoglobulin (Ig) gene somatic mutation. This process is tightly focused to rearranged VDJ segments and immediate flanking sequences. The mutation rate approaches 10-3/b.p./generation which is four orders of magnitude greater than that estimated for other eukaryotic genes. This process may be responsible for the development of self reactive antibody clones in autoimmune disorders and has also been implicated in the activation of certain oncogenes in B cell tumors. The biologic bases of Ig gene somatic hypermutation is unknown. We propose to localize regions of the Ig locus responsible for this process by cloning portions of the gene in close proximity to a marker gene, sup F. Mutations initiated and focused by Ig fragments may be expected to be introduced into this flanking target gene similar to what occurs in naturally occurring VDJ joinings and in non Ig sequences at the site of chromosomal translocations. Such changes will be recognized by a sensitive microbiological assay when this plasmid is used to transform indicator strains of E. Coli. A series of vector systems will be used to cycle Ig segments through various lymphoid environments ranging from cell lines to transgenic animals. Comparison of mutation rates initiated by different V regions may allow detection of recognition sequences highly sensitive to this process. Comparison of mutations that occur in different cell lineages may identify the presence of developmentally regulated cellular components which influence the mutational process. In addition to identifying the cellular and molecular basis of Ig Hypermutation, these experiments will determine the impact of this process on antibody diversity in the absence of antigen selection. These studies will lead to a broader understanding of the role of Ig mutation in the normal immune response, its potential contribution to autoimmunity and B cell malignancy, and will provide important insights into more general aspects of DNA mutagenesis.

免疫前抗体库的进一步多样化通过以下方式提供： 免疫球蛋白（IG）基因体细胞突变的独特过程。 这 该过程紧紧围绕重新安排的VDJ片段， 侧翼序列 突变率接近10-3/b. p./一代 这比其他国家的估计值高出四个数量级， 真核基因 这一过程可能是负责发展 自身免疫性疾病中的自身反应性抗体克隆， 参与B细胞肿瘤中某些癌基因的激活。 的 IG基因体细胞高突变的生物学基础尚不清楚。 我们建议 通过克隆定位负责该过程的IG基因座区域 与标记基因sup F紧密接近的基因部分。突变 由IG片段引发和聚焦的免疫球蛋白可能被引入 该侧翼靶基因类似于天然存在的VDJ中发生的基因， 在染色体易位位点的非IG序列中。 这些变化将通过灵敏的微生物测定法识别， 该质粒用于转化E.杆菌 一系列 的载体系统将用于循环IG片段通过各种 淋巴环境，从细胞系到转基因动物。 比较不同V区启动的突变率可能允许 识别序列的检测对此过程高度敏感。 比较发生在不同细胞谱系中的突变可以识别 存在发育调节的细胞成分， 影响突变过程。 除了识别细胞外 和IG超突变的分子基础，这些实验将确定 在没有抗原的情况下，该过程对抗体多样性的影响 选择. 这些研究将使人们更广泛地了解 正常免疫反应中的IG突变，其潜在的贡献 自身免疫和B细胞恶性肿瘤，并将提供重要的见解 DNA诱变的更一般的方面。